Is there any way to specify a legend before I attribute a featureclass in ARCMAP 10? I have a featureclass layer that has many thousands of polygons, I have to go through and individually attribute them, but it would be great if I could pre-define the symbology such that as I attribute polygons they will be filled in. More importantly, there will be approximately 150 different fill colors, I would like to be able to import the rgb values from a table, rather than manually input the values.
That is called creating attribute domain values. That is supported in geodatabases (any level).
A Quick Tour of Attribute Domains
After you create a domain and assign it to a layer then you would want to create a feature template for editing.